One of our electricians called me regarding annual IR scans they were starting this week. The difference this year is that an arc flash study has been executed and the equipment is now labeled. We previously determined PPE for IR scans by the NFPA tables (cat 2 PPE; removal of bolted covers >240V up to 600V). What level of PPE should be worn when removing covers to perform an IR scan on a 480V switchboard that is labeled with an AFIE of 80cal? The current standard says PPE is not required for IR scans, but the removal of covers still needs to be addressed. Seems to be a paradox since removing bolted covers is not considered energized work, but cat 2 PPE would not be adequate in the event of an AF incident involving this piece of equipment and exposure to a hazard over 40cal is not recommended. Iâve looked through NFPA 70E, but canât seem to find a definitive answer. Am I missing something?

There is a chance, when removing bolted covers, that the cover, a bolt, or a wrench gets dropped into the bus and causes an arc fault. Given that, you would need to match the incident energy, and wear a suit rated for 80 cal/cm2.

Best solution is to de-energize, install IR ports, and then re-energize and do your scans.

Regardless of whether the cover is bolted or hinged, there are documented OSHA arc flash incidents that have occurred. I can look up the exact details but in one case there was a sort of tray or ledge towards the bottom of the cover, probably the inner cover that goes over the breaker faces. An electrician placed a screwdriver on it and there was apparently a hole (maybe the bottom two knockouts were removed? unclear) and the screwdriver rolled into the panel and onto the bus bars. In a second case the panel was "repaired" by basically jamming a piece of sheet metal over some part of the panel and screwing the door closed. Except that in this case it wasn't just a booby trap for another electrician...it was so poorly done that when an unqualified person tried to operate a circuit breaker the piece of metal cut loose and fell into the bus bars. In another example outside of OSHA's files, an electrician went to access a panel mounted near a metal grinding area. When the electrician opened the panel, a pile of metal shaving dust laying on top of the panel fell down into the panel setting off an arcing fault.

Moral of the story here at least from the OSHA information is that improper maintenance can be deadly.

From personal experience my take on opening panels in general is:1. As of the 2014 NEC, all panels at all voltages must be marked as to whether they contain exposed parts behind the panel. This is also pretty much a requirement for opening a panel. So survey all your panels now and put the "danger high voltage" or "warning exposed parts" labels on all such panels if they can't be converted to a non-exposed status internally. Any of them that are exposed can pose an arc flash hazard. Any that are not are already protected against potential arc flash from opening the door. An example of panels that can't be fixed are the various panelboards and lighting panels that have an exposed bus. Most MCC and switchgear buckets, even the older ones, on the other hand are not exposed.2. All conductive materials, fasteners, and tools that can fall into the panel when it is removed must first be removed from the area. If they cannot be removed or secured, don't open the panel while energized. They make little cords and ropes specifically for securing wrenches from falling for instance and it takes only a minute to brush the pile of burned out fuses, handfulls of bolts, and the inches of wet mud off the top of the panel, and to put the rest of the tools back into your packets or back in the tool bag. Sometimes you can't actually achieve this if the panel is mounted in a poor location. No comment needed about mounted it in a location that it is rated for.3. Take a look at the panel itself. If it is hinged or circular (thing manhole cover), it's can't "fall into" the panel. Outside of these two obvious examples the most troublesome panels are panelboards and lighting panels. These typically have an inner cover that only covers the faces of the breakers and an outer cover that covers up the wiring. On some designs you can remove the outer cover with almost no risk of the panel falling into the enclosure but on many of them there is no way around this.4. Take a look at the condition of the box and the panel. If it's rusted out, you can't rely on the hinges to work properly.5. Finally once the panel is open, closely inspect the conductors. If they are way too long (not following NEC 110.12, or NECA 1-2000 or later) or worse still if the insulation is cracked and falling off the conductors due to previous overheating, there is a pretty good chance of an arc flash while attempting to close the door which is less of a risk while opening the door.

The NEC is not retroactive, therefore, has little impact on this thread.

First, the NEC section for low voltage is 110.27(C): "(C) Warning Signs. Entrances to rooms and other guarded locations that contain exp osed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter. The marking shall meet the requirements in 110.21(B)." For high voltage, it is 110.34(C). The only difference is that 110.34(C) requires very specific (and very non-ANSI Z535) wording: "DANGER -- HIGH VOLTAGE -- KEEP OUT", repeated in several places, and for cable trays the high voltage requirement changes to "DANGER -- HIGH VOLTAGE -- KEEP AWAY". in 392.18(H).

Although it is true that NEC is not retroactive due to the force of law behind it, invoking the NEC wins a lot of arguments for/against doing something.

Second, it solves a very real problem. If there are no exposed conductors behind a door then there is not only no need for a label in the first place but no need for shock protection when the door is opened. This would be true for instance of MOST bathrooms and office doors as an example but is also relevant to a whole host of electrical panel doors such as outer doors on outdoor enclosures and even switchgear rooms with enclosed switchgear where again...there is simply nothing exposed and there is no hazard when the door to the switchgear room is opened. Changing directions, there is also an awful lot of equipment out there where it is pretty obvious that the signage applies. For instance old switchgear where the only protection afforded to it is the chainlink fence that was installed in front of it years later or in installations that eschew the very idea of ever putting the covers back on the equipment, or where water is running out the front of the panel around the doors are obvious examples as is coming across equipment with obvious burn marks or deformed metal on the outside of the enclosure. Merely opening this type of equipment can be a shock hazard. Hence the rule and the signage requirement.

More interesting as an example are MCC's built in the last 30-40 years but especially in the last 10 years, as well as a huge amount of draw-out switchgear, class E1 and E2 starters, and so forth. The equipment is designed and built so that as long as it is properly installed and maintained, again there are no exposed conductors. But...I've seen a lot of poor installations and maintenance practices, too. This leaves a lot of normally perfectly safe equipment to question as to whether it is exposed when the door is opened or not.

So...applying the NEC rules both for current/new installations and retroactively takes all the guesswork out of whether or not opening a door presents a hazard to exposed electrical equipment.

The response for your specific question has not been addressed specifically on all the response posts I read.

You are right. NFPA 70E-2015 allows for IR scanning without PPE if you keep out of the restricted approach boundary. But the problem is that before you can do the IR scan, the covers have to be taken off. Catch 22.

Taking covers off is considered dangerous by the NFPA 70E 2015. Therefore, you will need to have the proper PPE for doing this work. This means, you will need to have PPE (see table in Appendix H) with a arc rating equal or larger than the arc flash incident energy shown in the arc flash label.

You will also need to have an energized electrical work permit to take the covers off.

The response for your specific question has not been addressed specifically on all the response posts I read.

You are right. NFPA 70E-2015 allows for IR scanning without PPE if you keep out of the restricted approach boundary. But the problem is that before you can do the IR scan, the covers have to be taken off. Catch 22.

Taking covers off is considered dangerous by the NFPA 70E 2015. Therefore, you will need to have the proper PPE for doing this work. This means, you will need to have PPE (see table in Appendix H) with a arc rating equal or larger than the arc flash incident energy shown in the arc flash label.

Not true. First off you mixed and matched things here. Since you invoked Annex H, you are not using the tables in Article 130. Thus you also must do a risk assessment under the 2015 edition. This is implied in prior editions but made explicit as of the 2015 edition. This means that you have to create a task table similar to the one in Article 130 or do something along similar lines.

Second, if we are looking at the task table, it carte blanche states that arc flash PPE is required for opening doors on equipment. The reason is because the tables are written in very general terms not considering specifics of a particular installation. As an example opening a door on a lot of equipment flat out will not cause an arc flash because the internal equipment is not exposed. Thus arc flash PPE is not required because it fails to meet the definition of an arc flash hazard...the employee is not interacting with the equipment in such a way that it is likely to cause an arcing fault. If we are not looking at the tables (because incident energy has been calculated, Annex H is in use, etc.), then the task table in Article 130 does not apply and a risk assessment must be done. Thus all the discussion is relevant.

[quote\You will also need to have an energized electrical work permit to take the covers off.[/quote]

First if we go back to the definition of working on energized electrical equipment, there are two types. There is "working on" which means that it is making circuit changes and there is diagnostic work which can include contact with equipment. The energized electrical work permit requirement specifically exempts diagnostic work so no permit is required if we treat opening and closing doors as a subtask of IR scans.

If we narrowly construe opening and closing doors to just this as a separate task then since no exposed, energized parts are being worked on at all, it is not energized work.

This approach if taken to its logical conclusion means that I can't open the door to the bathroom because the wall contains an energized receptacle and a lighting circuit and opening the door would require wearing arc flash PPE and wearing rubber gloves. Although most people might be concerned about the dexterity requirement necessary to use toilet paper effectively, my bigger concern would be finding a vendor to supply a drop seat in the bottom of the bibs for the 40 cal suit. Obviously diapers are not an effective solution because they definitely do not meet the "nonmelting" criteria!

Personally, I do not know of a more dangerous, yet common task, than removing the trim on a large switchboard or panelboard.

UL only requires a 1" creepage distance thru air at 480v and earlier it was 1/2". That forces a small margin for error where the mfg uses the min dimension.

I personally know of a Fortune 500 company where a thermographer forgot he had a screw driver in his hand when he was re-installing a large section of trim. The result was a severe burn and a million $ plus cost.

I have been doing IR electrical inspections for the past 13 years. I had covers removed from the backs of mcc and substation enclosures during the first year. At this time I was also getting up to speed on arc flash hazard. Though there were no incidents I saw that this task was potentially dangerous. I saw (still see) new equipment being designed, built and installed that ignores arc flash hazard mitigation with poor selection of (or omitting) protective devices and access for inspection. I also worked at one facility that required the electricians to remove bolted covers wearing lineman's gloves, talk about increasing the risk. So now there are places that I inspect that have not mitigated these issues and the equipment behind bolted covers are not inspected. These issues all seem to be a result of non-communication and or poor understanding in the facility maintenance hierarchy.

I agree 100% with the last two posts. And although there is definitely a hazard for panelboards with the inner/outer cover configuration, as the panelboard gets larger in size, the outer cover gets even more flimsy and increases the likelihood of dropping one into the panel as the panel size (and usually the hazard) grows. And this is only for front access. Rear access for the equipment that has it is even worse. A simple hinge definitely relieves about 99% of the hazard. A similar problem exists in the simple case of a lighting panel. Granted that an arc flash hazard really is not significant on MOST of them. This is in the cases where bus bar joints are "accessible" in the first place. As an example Powell switchgear in particular with their tubular busbar stuff basically makes access altogether impossible even where joints exist.

The problem with joints is that they are a source of arcing faults. According to NETA MTS there are 3 methods to inspect: IR scans, millivolt measurements, and torque testing. Taking these in turn:1. Torque testing cannot be done reliably except during initial torquing of the fastener. This is fasteners-101. It shouldn't even be in the NETA MTS standard in the first place. Torque testing "after" the fact is unreliable because about 80% of the initial tension disappears as the fastener relaxes during the first couple weeks of operation. Second attempting to test torque by "retorquing" will stretch the fastener further beyond it's design limits and result in more failures, not fewer.2. Millivolt measurements are not normally done online but I have seen a few experimental designs that can do this. The trouble is that millivolt measurements are vague at best and there is no standard. Readings can increase or decrease over time without any relationship as to joint integrity. Basically it's measuring the wrong thing. This method has been used for quite a while with large batteries only because there's no other practical method.3. IR scans aside from obvious problems with getting accurate readings are the best option out of all of these but are only valid when the joint is under load and when the load is about the same every time, and only when the joint is actually visible. Perhaps the best version that I've seen for this uses fiber temperature sensors located at each joint at a cost of about $150/sensor plus the cost of the sensor transmitter but justifying that level of cost isn't easy even when factoring "wrench time" as a cost. And even notwithstanding all of this, there's that pesky safe access problem. IR scanning is actually safer with "open" equipment designs but I'm not advocating a return to live front construction either.

Two problems with IR ports. The first is that except for very small equation such as size 1 starters, even with the largest windows available (4"), you can't possibly get to the angle required to image all the things inside an enclosure where you need to get a view of it. Think for instance about imaging the lugs on the top and bottom of a circuit breaker in a starter and then trying to get the contactor as well and the lugs for the motor. Even in a size 1 starter it's doubtful you can get everything. Just try one and you'll see what I mean. About the only way that this could ever work is if the entire front face was made of a clear material.

Second problem is that the image is distorted. As the viewing angle increases away from perpendicular to the port, it distorts the image. There have been improvements but it is impossible to get around this issue.

And with the idea that the entire front face is a clear material...this is not as ridiculous as it sounds. Most covers for power resistors are perforated plate or metal mesh. Some switchgear comes with an inner door that is similarly perforated for viewing. I can easily envision taking a door and cutting holes in it with a water knife or laser and then backing it with a sheet of plastic for dust/water intrusion. The biggest disadvantage to such a design is the additional cost.

In a previous response, PaulEngr stated " NOT TRUE " to one of my comments.

As I have said before, I have been wrong many times in my long life. In this case, I believe Paul is wrong.

Now, in my thread, I talked about several things. I do not know exactly which part is " NOT TRUE ". Therefore, I will dissect Paul's comments with my responses.

Paul's Comment:

"Not true. First off you mixed and matched things here. Since you invoked Annex H, you are not using the tables in Article 130."

My Response to his comment:

Yes, I invoked Annex H. In this particular case, there is an AFHA done and the panel has a label with a calculated AFIE. Therefore, the proper procedure is to use Annex H to obtain the proper PPE. Tables of Article 130 are irrelevant in this case, and therefore, I did not mention them. Since I did not mention these tables, how can it be asserted that I mixed and matched things here?

Paul's Comment:

Thus you also must do a risk assessment under the 2015 edition. This is implied in prior editions but made explicit as of the 2015 edition. This means that you have to create a task table similar to the one in Article 130 or do something along similar lines.

My Response to his Comment:

Paul is right. Starting from version of 2015 the NFPA 70E requires a risk analysis. The risk analysis will have to be specific for the activity and equipment. Taking covers on a specific panel with a specific characteristic (i.e. AFIE, voltage, maintenance records, etc.). I did not mention that a risk analysis should not be conducted. So the his comment of " NOT TRUE "probably did not apply to the unmentioned risk analysis.

Also, it is possible that AFTER a risk analysis performed by the responsible safety person, he/she determines that the risk of taking covers is acceptable and PPE is not required. Highly unlikely but possible. In that case, my mentioning of PPE according to Annex H is irrelevant. Maybe, this is why Paul commented that I was incorrect. Who knows.

Paul's Comment:

Second, if we are looking at the task table, it carte blanche states that arc flash PPE is required for opening doors on equipment. The reason is because the tables are written in very general terms not considering specifics of a particular installation.

My Response to his Comment:

I agree 100%. But I did not argue against this concept. So how can something be "NOT TRUE" if it was not mentioned?

Paul's Comment:

As an example opening a door on a lot of equipment flat out will not cause an arc flash because the internal equipment is not exposed. Thus arc flash PPE is not required because it fails to meet the definition of an arc flash hazard...the employee is not interacting with the equipment in such a way that it is likely to cause an arcing fault.

My Response to his Comment:

The âNOT EXPOSEDâ part in Paul's comment is debatable.

NFPA 70E-2015 (the NEC 2014 has the same definition) defines EXPOSED as:

"Capable of being inadvertently touched or approached nearer than a safe distance by a person".

So this sentence has two parts connected with an OR. If any of the two parts is satisfied, then you have an EXPOSED electrical part. You might not satisfy the first part, but if the second is satisfied you have an EXPOSED part.

First part: I agree that in many cases, an electrical panel has insulated energized parts. In that case, the QP will not be able to inadvertently touch them, and therefore will meet the first requirement of NOT being EXPOSED.

Second part: But the second part of the definition of EXPOSED is interesting. It says that you will have an EXPOSURE if you are capable of approaching the energized part nearer than a safe distance. So even if a part is insulated, you might be still able to approach an energized part so close that you are not safe anymore. This can't apply to shock (covered in the first part) but to arc flash. An insulated energized part might still pose a real threat of injury in case of an arc flash if you approach it very closely. Arc flash events occur even without human interaction. Could be an overvoltage (lightning strike hitting the nearby power lines). I have been witness of an arc flash on a MV starter, when the panel was enclosed. I have heard many time of arc flashes with the covers closed with no human interaction. I have to concede that is unlikely, but it is possible. Otherwise this second part would not be here. So, unless a risk analysis has been carried out and determined that the open panel with insulated electrical parts does not pose a risk, I would have considered it as EXPOSED.

Please read the comment of the NFPA 70E-2015 Handbook under the definition of "Guarded". This comments will solidify the argument that even if you have insulted energized parts, if you closely approach the equipment, you still MIGHT be risking injuries due to arc flash.

âIt is unlikely that people or objects will contact equipment, circuits, or conductors that are guarded. Although guarding provides protection from exposure to shock or electrocution, it is still possible for persons to be exposed to arc flash hazards.â

Paul's Comment:

If we are not looking at the tables (because incident energy has been calculated, Annex H is in use, etc.), then the task table in Article 130 does not apply and a risk assessment must be done. Thus all the discussion is relevant.

My Response to his Comment:

Agree, but I did not argue against this point. I never mentioned anything with tables. So all these comments about the tables is irrelevant and cannot be judge if my statements are true or not.

I just stated that in order to take covers off, you need to have proper PPE according to the AFIE that was calculated and to do so, you have to look at the Annex H for guidance.

Paul's Comment:

First if we go back to the definition of working on energized electrical equipment, there are two types. There is "working on" which means that it is making circuit changes and there is diagnostic work which can include contact with equipment.

My Response to his Comment:

Agree, but I did not argue against this point.

Paul's Comment:

The energized electrical work permit requirement specifically exempts diagnostic work so no permit is required if we treat opening and closing doors as a subtask of IR scans.

My Response to his Comment:

I ABSOLUTELY do not agree. Taking covers on or off (without a risk analysis that specifically establishes that there is an acceptable risk) is considered dangerous! I believe most of us agree with this statement. Taking covers on or off is considered energized work (in the process of taking the covers, you will have access to the energized parts, a screw driver or a bolt or the cover itself might fall and touch an energized part.

Paul's Comment:

If we narrowly construe opening and closing doors to just this as a separate task then since no exposed, energized parts are being worked on at all, it is not energized work.âMy Response to his Comment:

I ABSOLUTELY do not agree. When you are in the process of taking covers, part of the process is done when the energized parts are accessible. Maybe at the beginning, when you are talking the bolts off, you still have the energized parts guarded, but when you start removing the covers, you have access to the energized parts, and the corner of the cover might touch these energized parts, or a screw driver or bolt is dropped, etc. It has happened many times. It almost happened to me when I was taking the covers of the primary connections of a transformer, I have witness many times an electrician taking covers and dropping his screw driver and bolts INSIDE the energized panel.

Paul's Comment:

This approach if taken to its logical conclusion means that I can't open the door to the bathroom because the wall contains an energized receptacle and a lighting circuit and opening the door would require wearing arc flash PPE and wearing rubber gloves. Although most people might be concerned about the dexterity requirement necessary to use toilet paper effectively, my bigger concern would be finding a vendor to supply a drop seat in the bottom of the bibs for the 40 cal suit. Obviously diapers are not an effective solution because they definitely do not meet the "nonmelting" criteria!

My Response to his Comment:

I guess you can argue that if you want, but you will be considering an extremist, which I know you are not. We are talking about three phase industrial electrical distribution systems, with a minimum of 208 V between phases. Bathrooms are not in this league. Now, I have to recognize your humoristic twist as a very funny one, but it does not add anything to the intellectual discussion.

In a previous response, PaulEngr stated " NOT TRUE " to one of my comments.

As I have said before, I have been wrong many times in my long life. In this case, I believe Paul is wrong.

Now, in my thread, I talked about several things. I do not know exactly which part is " NOT TRUE ". Therefore, I will dissect Paul's comments with my responses.

I quoted everything but my "not true" comment only relates to the last sentence: My mistake and thus we got off on the wrong foot here. So I'll take the blame where it is deserved.

Quote:

Taking covers off is considered dangerous by the NFPA 70E 2015. Therefore, you will need to have the proper PPE for doing this work. This means, you will need to have PPE (see table in Appendix H) with a arc rating equal or larger than the arc flash incident energy shown in the arc flash label.

I disagree only with the statement that "taking covers off is considered dangerous by the NFPA 70E-2015". I think we are in agreement with almost everything else. This is indeed the conclusion in the task tables. It is not the conclusion if you are using the other method. Since 70E doesn't give a specific definition to doing your own risk assessment, let's just call it "user defined". In this respect 70E is utterly silent. They don't even give you a table of risk assessment methods or standards as they do with the hazard assessment method given in Annex D. The only thing that exists in 70E-2015 is Annex F that is a load of garbage. We could take the approach that all electrical equipment is inherently dangerous in which case we get all kinds of idiotic situations such as requiring arc flash and shock protection PPE to make a pot of coffee. We could also leave it up to a safety specialist who is not a qualified person under 70E and this would also be a disaster in terms of generating all kinds of stupid and unworkable procedures. Or we could use one of the risk assessment standards that exists.

As to my argument that opening covers is inherently dangerous, let's take two examples from the exact same piece of equipment. I'm specifically thinking of 1980's vintage ABB and similarly built low voltage switchgear but most of it follows a similar design concept. The first example is the rear cover over bus bars on some switchgear. These panels are usually quite large (80"x36" and heavy, and if they are bolted on, it is very easy to accidentally drop one into the panel. In this circumstance it probably goes without saying that the incident energy is going to be a big number. This definitely without a doubt meets the definition of a "dangerous" task if done while energized.

Now let's consider the same switchgear from the front side and I'll add in that this is the design that you would typically see from several manufacturers where the circuit breaker itself is racked in on rails. It is physically quite large and takes up most of the enclosure, and the front cover allows the front face of the circuit breaker to show through it. All of the energized parts are several inches back and it is not possible to inadvertently come into contact with them except by intentionally reaching back around the circuit breaker. If there are no "add ons" then the cover itself is just that, a hinged cover that mostly just covers up the gap between the circuit breaker body and the enclosure sidewalls. With the door open even while racking the breaker in/out, there is nothing that meets the definition of exposed. This is a very common design with several manufacturers.

Under the table based method, both situations would require arc flash PPE for opening the doors. If we do a risk assessment though we would have two different conclusions if we looked at each door separately.

Quote:

Also, it is possible that AFTER a risk analysis performed by the responsible safety person, he/she determines that the risk of taking covers is acceptable and PPE is not required. Highly unlikely but possible. In that case, my mentioning of PPE according to Annex H is irrelevant. Maybe, this is why Paul commented that I was incorrect. Who knows.

Yes but this is also suggesting that the analysis wasn't done following any of the standards for this activity. There are a lot of risk assessment standards out there but they all follow a common procedure. As per "Electrical Hazard Analysis from a PSM Perspective", IEEE ESW2014-12 as an example, "PHAs must be done by a multi-disciplined team involving at least one member who has significant knowledge and experience with the process or system. One member must be knowledgeable of the overall PHA process and the hazard analysis methodologies utilized. The remainder of the team should include knowledgeable technical and âhands-onâ personnel such as; operators, mechanics, electricians, software engineers." In practice it is virtually impossible to be the facilitator of the team and a team member at the same time. It is best for the safety professional to be a full fledged member, not try to wear both hats as both the facilitator and a team member. By nature safety professionals have general (but not specific) knowledge of the tasks involved and they are risk averse since quite often their performance is based on how many accidents occur. On the other hand other members such as electricians have a primary responsibility to "get the job done" with safety more often than not taking a back seat (no matter what they may actually say or do). So somewhere between "don't do anything" and "get 'er done" we need to find a reasonable consensus. You can't get there if either party has sole control over the process.

Quote:

The âNOT EXPOSEDâ part in Paul's comment is debatable.

NFPA 70E-2015 (the NEC 2014 has the same definition) defines EXPOSED as:

"Capable of being inadvertently touched or approached nearer than a safe distance by a person".

So this sentence has two parts connected with an OR. If any of the two parts is satisfied, then you have an EXPOSED electrical part. You might not satisfy the first part, but if the second is satisfied you have an EXPOSED part.

First part: I agree that in many cases, an electrical panel has insulated energized parts. In that case, the QP will not be able to inadvertently touch them, and therefore will meet the first requirement of NOT being EXPOSED.

Second part: But the second part of the definition of EXPOSED is interesting. It says that you will have an EXPOSURE if you are capable of approaching the energized part nearer than a safe distance. So even if a part is insulated, you might be still able to approach an energized part so close that you are not safe anymore. This can't apply to shock (covered in the first part) but to arc flash. An insulated energized part might still pose a real threat of injury in case of an arc flash if you approach it very closely. Arc flash events occur even without human interaction. Could be an overvoltage (lightning strike hitting the nearby power lines). I have been witness of an arc flash on a MV starter, when the panel was enclosed. I have heard many time of arc flashes with the covers closed with no human interaction. I have to concede that is unlikely, but it is possible. Otherwise this second part would not be here. So, unless a risk analysis has been carried out and determined that the open panel with insulated electrical parts does not pose a risk, I would have considered it as EXPOSED.[/qupte]

Full definition: "Capable of being inadvertently touched or approached nearer than a safe distance by a person. It is applied to electrical conductors or circuit parts that are not suitably guarded, isolated, or insulated."

Disagree here. I think we can agree 100% with respect to shock hazards. However I break the "or" phrasing down somewhat differently. The phrasing is intended to capture flashovers. At low voltage where direct contact is necessary the first phrase applies. As voltages increase (generally held to be above 150 V) direct contact is no longer necessary. The second sentence clarifies that equipment that is guarded, isolated, or insulated is not exposed. You can't really get a shock from equipment that is insulated. If it's not insulated but has a jacket that is insufficient as insulation, it is defined as "covered". This is in the definitions in NEC.

Quote:

Please read the comment of the NFPA 70E-2015 Handbook under the definition of "Guarded". This comments will solidify the argument that even if you have insulted energized parts, if you closely approach the equipment, you still MIGHT be risking injuries due to arc flash.

âIt is unlikely that people or objects will contact equipment, circuits, or conductors that are guarded. Although guarding provides protection from exposure to shock or electrocution, it is still possible for persons to be exposed to arc flash hazards.â

"Exposed" as a condition on arc flash is historical. In NFPA 70E 2000, 2004, and 2008 editions an energized work permit was only required when a shock hazard existed. All of the arc flash hazard requirements followed 130.1 as they do now but there was a lot of confusion because it appeared that arc flash was just another consequence of a shock. In cases where employees are working on or near exposed, energized equipment one of the three types of causes of arcing faults are human error cases such as a dropped tool, drilling through busbars where the drill hits the enclosure, or blindly inserting or removing conductive parts from a space with energized parts inside it. Thus it made sense to consider shock hazards as a condition on arc flash for this case.

But another large class of arc flash injuries have occurred whenever conductors are either separated or connected slowly enough that they draw an arc that is not immediately extinguished. This occurs for example with opening or closing some non-load break rated substation switches, racking bus cans, breakers, and MCC buckets on/off busses, terminating or determinating wires, and tightening or adjusting fasteners. The common thread here is not whether or not there are exposed conductors and with racking in particular typically they are not exposed but the interaction that the employee is having with the exposed equipment. Thus the definition of an arc flash changed to include the interaction and in 2012 the energized work permit requirement was extended to include arc flash hazards independent of shock.

A third class of arcing faults (not necessarily arc flash injuries) comes from equipment under normal (or abnormal) operation that has an arcing fault such as due to a lightning strike or a switching transient as you described earlier. In this case a person could be just walking by or performing some activity which in itself may even trigger the arc flash but the activity is not the root cause of the arc flash. With regards to these more or less "acts of God" cases, the 70E Committee has stated several times in several responses to public inputs to 70E that just walking by is not considered hazardous and they have also made statements in several places in the current 2015 edition that normal operation of equipment is not an arc flash hazard. These events are in the same category as protecting against meteor strikes (do nothing). In a strict sense an arc flash hazard always exists but 70E uses the same "likelihood" or limited definition approach that is taken with shock hazards and also that NFPA 499 among others takes with respect to hazardous locations. As with those other cases 70E does not say that an arc flash hazard is simply "unlikely" but that a hazard (that we can or should address) does not exist, even if in the strictest sense the possibility exists.

The alternative is to look at all possible arcing faults. Then we are back to the knee-jerk safety manager scenario where all electrical equipment is inherently dangerous and we start having either a bunch of stupid safety rules where credibility goes out the window or a huge laundry list of exceptions that never ends. That's simply not true and not supported by the standard.

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Paul's Comment:

The energized electrical work permit requirement specifically exempts diagnostic work so no permit is required if we treat opening and closing doors as a subtask of IR scans.

My Response to his Comment:

I ABSOLUTELY do not agree. Taking covers on or off (without a risk analysis that specifically establishes that there is an acceptable risk) is considered dangerous! I believe most of us agree with this statement. Taking covers on or off is considered energized work (in the process of taking the covers, you will have access to the energized parts, a screw driver or a bolt or the cover itself might fall and touch an energized part.

I've worked in facilities that failed to understand that part of the energized work permit requirement is the type of work (is it diagnostic or not). Thus we fall into the trap that an energized work permit would be required for virtually all work, even diagnostic work, culminating in the most silly of circumstances that an energized work permit is required to perform LOTO because testing for absence of voltage is energized work, so then we just require an energized work permit for all work. I'm not making this up.

This is far different from whether or not PPE is required. They are two different issues altogether although casually reading through 70E seems to suggest that they are linked together and that's my point here, not whether or not PPE would be required.

And you second comment though comes back to my argument about whether or not PPE would be required. If there is nothing exposed inside the panels then whether or not the fasteners or even the entire panel falls into the enclosure cannot cause a shock or arcing fault. If the panel is perfectly round (the manhole cover argument) or hinged and the fasteners are "captured" or otherwise designed so that they can't fall out then there is nothing to fall into the panel so even if there are exposed conductors on the other side, an arcing fault and/or shock hazard cannot occur.

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Paul's Comment:

If we narrowly construe opening and closing doors to just this as a separate task then since no exposed, energized parts are being worked on at all, it is not energized work.âMy Response to his Comment:

I ABSOLUTELY do not agree. When you are in the process of taking covers, part of the process is done when the energized parts are accessible. Maybe at the beginning, when you are talking the bolts off, you still have the energized parts guarded, but when you start removing the covers, you have access to the energized parts, and the corner of the cover might touch these energized parts, or a screw driver or bolt is dropped, etc. It has happened many times. It almost happened to me when I was taking the covers of the primary connections of a transformer, I have witness many times an electrician taking covers and dropping his screw driver and bolts INSIDE the energized panel.

Paul's Comment:

We're talking about two different animals. Whether or not the equipment is energized doesn't change anything because at this point since we can't test for absence of voltage without removing the cover, we can't establish this and must default to assuming that the equipment is energized. As to whether or not the equipment is guarded, is it guarded with the cover already taken off the equipment? In the case of most dry transformers I'd definitely agree that it's exposed. And in that case the fasteners are anything but captured and the panels are generally not designed as doors that can only swing outward so we have an arc flash potential here. But flip that around and consider the simple combination starter enclosure. The door is hinged and even if it has bolts, they are captured bolts. There are no parts to fall in when the door is opened. And if everything is terminated properly, all the conductors are guarded. If you are probing around with an uninsulated screwdriver in the starter bucket then that makes them exposed but with an insulated screwdriver or the original example (IR scans), nothing is ever exposed. So these are two examples of the two extremes (arc flash is very likely, arc flash is very unlikely), even with something as simple as "removing covers".

Quote:

This approach if taken to its logical conclusion means that I can't open the door to the bathroom because the wall contains an energized receptacle and a lighting circuit and opening the door would require wearing arc flash PPE and wearing rubber gloves. Although most people might be concerned about the dexterity requirement necessary to use toilet paper effectively, my bigger concern would be finding a vendor to supply a drop seat in the bottom of the bibs for the 40 cal suit. Obviously diapers are not an effective solution because they definitely do not meet the "nonmelting" criteria!

My Response to his Comment:

I guess you can argue that if you want, but you will be considering an extremist, which I know you are not. We are talking about three phase industrial electrical distribution systems, with a minimum of 208 V between phases. Bathrooms are not in this league. Now, I have to recognize your humoristic twist as a very funny one, but it does not add anything to the intellectual discussion.

Taking an invalid statement to a very illogical and unrealistic conclusion is an effective strategy to show an error in the logic of the statement. At one time a safety manager stated that we were not going to differentiate between confined spaces and permit required confined spaces as per OSHA regualtion. So I placed a "confined space, permit required" sign on the bathroom door of a single occupant bathroom used frequently by the safety manager. It met all the requirements of a confined space (limited means of egress, big enough that you can get in it, etc.). He argued that flatulence is not toxic gas and that's why its not a permit required confined space, which made my argument about the difference.

As a straw man argument consider the following:

Types of covers that do not require arc flash PPE:A. Hinged doors or circular covers that are visually in good working order (not racked or corroded) with captive fasteners. All dust, dirt, mud, loose parts, tools, and any other accumulations of loose material on top of or around the edges of the door must be cleared. Equipment must be in good working condition (properly designed, installed, maintained, and not recently faulted, and not showing external signs of damage, contamination, or deterioration).B. Covers that are visually in good working order (not racked or corroded) with captive fasteners where the enclosed parts are not exposed. All dust, dirt, mud, loose parts, tools, and any other accumulations of loose material on top of or around the edges of the door must be cleared. Only insulated tools may be used for opening. Equipment must be in good working condition (properly designed, installed, maintained, and not recently faulted, and not showing external signs of damage, contamination, or deterioration).C. Covers over equipment that is less than 50 Volts AC or 100 Volts DC.D. Covers over equipment where the incident energy is less than 1.2 cal/cm2.E. Covers over equipment where an arc flash cannot occur such as Class A (limited energy) power circuits.All other covers require arc flash PPE while opening or closing.

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